1. Field of the Invention
The present invention relates to a method and system for detecting the presence of foreign particles within a fluid filled transparent bottle, such as a soft drink bottle. More specifically, the present invention relates to a system and method for detecting the presence of foreign particles within a bottle having distinctive optical characteristics in its side wall and distinctive logo printed thereon, which ordinarily would have the same effect on an optical detection system as a foreign particle disposed within the bottle.
2. Prior Art
Heretofore systems have been designed for detecting moving foreign particles within liquid filled containers. Systems of this type can be found in U.S. Pat. No. 3,598,907 to Drinkuth issued in August, 1971; U.S. Pat. No. 3,777,169 to Walter et al issued in December, 1973; and U.S. Pat. No. 3,765,533 to Stevenson et at issued in October, 1973. Each of the above patents disclose a system for detecting foreign particles within a liquid disposed in a container including:
Means for swirling the liquid to generate movement of the particles; PA1 Video camera means for taking pictures of the bottle being inspected and liquids contained therein at first and second points in time; PA1 Means for storing the pictures taken at the respective times; and PA1 Means for comparing the pictures stored in order to detect motion of the particles within the liquid, and thus their presence.
The systems of the above patents suffer from the following disadvantages. The prior art systems in the above patents utilize a video or analog sensing mechanism such as a conventional television camera. Thus, the inspection is generally accompanied by a surplus of generated data and is processed by such means as edge detection systems and supression systems.
In addition the systems of the above patents implement particle motion in the liquids by spinning the containers about their vertical axis rather than inverting the containers. Thus, light particles within the containers often are not agitated sufficiently to detect motion thereof.
The systems of the above patents suffer from the further disadvantage that all images of the article under inspection are recorded by a single camera device at a single station rather than recording the images in an in-line process wherein the first image is recorded at a first station on a rapidly moving conveyor and the second image is recorded at a second station on the rapidly moving conveyor. With the systems of the above patents, therefore, the object under inspection must remain for a considerable period of time at the inspection station in order to facilitate the recording of two images.
A further prior art patent of interest is U.S. Pat. No. 3,942,022 to Stumpf. The system of Stumpf discloses the use of a photodiode matrix array to detect movement of a light image. The Stumpf system detects motion by using a photodiode matrix array and scanning the output of the array at a time T and again scanning the output of the same array at a time delta T ( .DELTA. T). The results of the scan are then compared to indicate the presence of motion. The system disclosed in the Stumpf patent is not concerned with the high speed inspection of a plurality of containers moving along a conveyor.
Of additional interest with respect to prior art systems are U.S. Pat. No. 3,835,332 to Bridges issued in September, 1974 and U.S. Pat. No. 3,956,629 to Gomm issued in May, 1976. These patents are of interest in that they utilize a photodiode matrix array for inspecting an object for flaws wherein first and second images of the object are detected and compared, the first image being a reference standard for determining whether or not a defect exists in the object. However, in both of these patents the images compared are generated by the same camera and these patents are not concerned with high speed in-line inspection of containers.
Other U.S. Patents of interest which disclose the use of photodiode arrays for detecting flaws in objects are U.S. Pat. No. 3,886,356 to Gomm et al issued May, 1975 and U.S. Pat. No. 3,877,821 to Price et al issued April, 1975.
None of the above prior art patents disclose a system or method for suitably inspecting in rapid succession a plurality of transparent optically-irregular fluid-filled containers for the presence of foreign particles therein in a manner suitable for use with high speed soft drink filling equipment.